Mobile communication systems are developed to provide subscribers with voice communication services on the move. With rapid technological advancement, the mobile communication systems have evolved to support high speed data communication services as well as the standard voice communication services. However, the limited resource and user requirements for higher speed services in the current mobile communication system spur the evolution to more advanced mobile communication systems.
The 3rd Generation Partnership Project (3GPP) Long Term Evolution-Advanced (LTE-A) is a technology for implementing a high speed packet-based communication at the data rate of up to 1 Gbps. In LTE-A, a User Equipment (UE) is served by an evolved Node B (eNB) in multiple cells but sends feedback to the respective cells through a Primary cell (PCell). In LTE-A, all the cells configured for a UE operate in Frequency Division Duplex (FDD) or Time Division Duplex (TDD). The TDD can be classified into one of a static TDD in which the Uplink-Downlink (UL-DL) configuration is fixed and a dynamic TDD in which the UL-DL configuration varies according to system information, a higher layer, or a downlink common control channel.
In the state that a cell under the control of an eNB operates in the FDD mode, if a frequency band is added, it is likely to apply TDD to this new frequency band. This is because FDD uses two separate frequency bands for DL and UL.
Accordingly, when multiple cells operating in different duplexing modes coexist due to the addition of limited frequency band as aforementioned or due to other reasons, there is a need of a method for transmitting the control channels corresponding to the data transmitted in the different cells efficiently. In a case where the feedback for multiple cells should be transmitted through the PCell in association with the uplink control channel corresponding to the downlink data, there is also a need of a technique for the UE to transmit the feedback to the cells operating with different frame structures through the PCell. Furthermore, there is a need of a technique for the eNB to schedule the uplink data of the UE in association with the downlink control channel corresponding to uplink data and transmit the downlink control channel corresponding to the uplink data.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.